Rheological properties of aqueous konjac glucomannan dispersions and its mixtures with soybean protein isolate

The properties of konjac glucomannan(KGM) aqueous dispersions and the mixtures of KGNVsoybean protein isolate(SPI) were investigated by theological measurements. It is found that the changes in storage shear modulus(G'), loss shear modulus(G '') and viscosity(eta) for KGM aqueous dispersions essentially depend on the nature of the added thiourea, urea, sugar, and lyotropic series salts. The salting-out effect of adding Na2SO4, is quite remarkable on KGM, which increases both the G', G '' and eta of the KGM aqueous dispersions evidently whereas the effects of adding NaCl, NaNO3 and NaSCN are not significant. In the case of mixing SPI with KGM, the addition of SPI causes a significant increase in the viscoelasticity of the mixture. This fact indicates that an interaction between the two biopolymers might be due to the occurrence of enhanced hydrogen bonding between KGM and SPI.